IJ41667: CRASH DURING JIT COMPILATION

APAR status

• Closed as program error.

Error description

• Error Message: JVM terminates with GPF in libj9jit29. The
  javacore indicates that a method was being compiled at the time:
  1XHEXCPMODULE  Compiling method: <method>
  and the current thread with be a JIT compilation thread.
  .
  Stack Trace: The only reports so far have failed during local
  value propagation, but it seems likely that other locations for
  the failure could occur
  0x00007fde014537aa
  {libj9jit29.so}{_ZN3OMR16ValuePropagation11findOutEdgeERN2TR12fo
  rward_listIPNS1_7CFGEdgeENS1_15typed_allocatorIS4_RNS1_6RegionEE
  EEEPNS1_7CFGNodeE} <OSB>0x7fddfde7a148<CSB>
  0x00007fde0157df19
  {libj9jit29.so}{_ZL18constrainIfcmpeqnePN3OMR16ValuePropagationE
  PN2TR4NodeEb} <OSB>0x7fddfde7a150<CSB>
  0x00007fde0153717d
  {libj9jit29.so}{_ZN3OMR16ValuePropagation10launchNodeEPN2TR4Node
  ES3_i} <OSB>0x7fddfde7a250<CSB>
  0x00007fde01537511
  {libj9jit29.so}{_ZN3OMR16ValuePropagation12processTreesEPN2TR7Tr
  eeTopES3_} <OSB>0x7fddfde7a290<CSB>
  0x00007fde01537a8e
  {libj9jit29.so}{_ZN2TR21LocalValuePropagation12processBlockEPNS_
  7TreeTopE} <OSB>0x7fddfde7a2f0<CSB>
  0x00007fde01538048
  {libj9jit29.so}{_ZN2TR21LocalValuePropagation7performEv}
  <OSB>0x7fddfde7a350<CSB>
  0x00007fde013fdf67
  {libj9jit29.so}{_ZN3OMR9Optimizer19performOptimizationEPK20Optim
  izationStrategyiii} <OSB>0x7fddfde7a370<CSB>
  .
  

Local fix

• The problem occurs during global value propagation, so disabling
  this optimisation for the failing method should allow the
  compilation to proceed normally. For example for a method
  packageA.packageB.MyClass.myMethod the following JVM option
  could be used:
  -Xjit:{packageA/packageB/Myclass.myMethod(*}(disableGlobalVP)
  Note that there can only be one active -Xjit option on the Java
  command line, so if there is an existing one in use it must be
  merged with the above.
  

Problem summary

• This problem is caused by a rare edge case in global value
  propagation, discussed in detail in
  https://github.com/eclipse/omr/issues/6623. It results in
  corrupted nodes in the trees at the end of the GVP pass, and
  later optimisations then crash when processing these nodes. A
  good indication that this problem is involved would be the
  presence of nodes with missing children after GVP. If a jitdump
  is created during the crash this can be inspected for signs of
  the problem. A possible hint of the error is the presence of
  lines such as:
  TREE VERIFICATION ERROR -- treetop node <OSB>0x7fdc46088930<CSB>
  with ref count -2 (e.g. 13959)
  in the jitdump.
  

Problem conclusion

• The problem is caused when GVP processes a loop using multiple
  passes, scheduling a node for one of the delayed transformations
  in the first pass, but then removing the node and others during
  the second pass. This has been mitigated by making the delayed
  transformation check that the node was not removed from the
  trees.
  .
  This APAR will be fixed in the following Releases:
  .
  IBM SDK, Java Technology Edition
     8    SR7 FP20  (8.0.7.20)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  maintenance can be found at:
             https://www.ibm.com/support/pages/java-sdk
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels